yeh, Harry's proboly right those are two inexpensive parts that should be replaced anyway... can I call you harry? I think it's cute...
anyway, it may just be the plug because of all that oil, I know you said it had spark but sometimes a "nearly broken plug" can spark in open air, but not under compression. I had a mystery problem like that once, and I did all of the above... it worked alot better but still kinda weird. so I replaced the(what seemed to be OK) plug and Perfecto!
Also it is supposed to shoot stuff outta the exhaust port, thats just how the motor works.